Introduction Although the Accreditation Council for Graduate Medical Education (ACGME) has recently placed limitations on resident work hours in an attempt to reduce fatigue-related medical errors, the practice of working for more than 24 h consecutively remains the cornerstone of American postgraduate medical education. Moreover, a 1999 report from the Institute of Medicine revealed that between 48,000 and 98,000 deaths each year occur due to a medical error [1]. A recent randomized trial reported that interns working extended-duration shifts (defined as at least 24 h continuously at work) had significantly more polysomnographically recorded attentional failures and made significantly more serious medical errors than those scheduled to work shifts 16 h or longer [2,3]. However, that trial was not large enough to determine whether extended-duration work shifts increased the risk of preventable adverse events, for example injury due to a non-intercepted serious error in medical management, although a trend in that direction was reported [3]. To address the impact of extended-duration work shifts on patient safety in a large and more diverse population of interns, we conducted a nationwide study of US interns in which we collected monthly data on self-reported attentional failures (defined as “nodding off or falling asleep” during patient-care or educational activities), significant medical errors, and preventable adverse events (including fatalities). Methods Details regarding participant recruitment have been described in detail elsewhere [4]. Briefly, in the spring of 2002, we sent email announcements to all individuals who successfully matched to a residency program in the National Residency Matching Program (NRMP) and to all known email addresses of graduating fourth-year medical students of US programs in an effort to reach as many of the 18,447 individuals who matched to residencies via the NRMP. These emails directed potential participants to a secure Web site which provided detailed information about the study and enabled participants to provide electronic informed consent. In June 2002, an email was sent to the 3,429 interns who had volunteered to participate in the study, and they were directed to a password-coded secure Web site to complete a baseline survey that solicited background data. From July 2002 to May 2003, on the 28th day of each month, emails were sent to those who had completed the baseline survey (the study cohort) to direct participants to a secure Web site to complete a monthly survey. Monthly surveys were available on the Web site until the 27th day of the next month, and we ensured that each participant answered each monthly survey only once. The monthly survey contained detailed questions regarding work hours, sleep, activities during the month, number of days off, and the number of extended-duration work shifts. Among the 60 questions they were asked each month, interns were asked to report whether they had made a significant medical error (“Do you believe sleep deprivation or fatigue caused you to make a significant medical error?” [henceforth referred to here as “fatigue-related errors”] and “Do you believe you made any significant medical errors other than due to sleep deprivation or fatigue?” [henceforth referred to here as “non-fatigue-related errors”]). If they answered affirmatively, they were directed to a supplementary survey that elicited further information about the error(s), including whether they had resulted in an adverse patient outcome (i.e., a preventable adverse event) or a patient fatality (i.e., a preventable adverse event resulting in a fatality). Moreover, interns were also asked to report how many times they had nodded off or had fallen asleep (attentional failure) during specific patient-care activities (during surgery and while talking to, or examining, patients) and educational activities (during rounds with the attending physicians and during lectures, seminars, or grand rounds). The remaining questions addressed secondary outcomes such as caffeine usage, health, and mood, and served as distracters for the main hypothesis. The Web sites were hosted and maintained by Pearson Assessments (http://www.pearsonncs.com). Data were transmitted electronically on a weekly basis through secure means from Pearson Assessments to the Brigham and Women's Hospital. All demographic and potentially identifiable data were then stored separately from the main database. A certificate of confidentiality was issued by the Centers for Disease Control; the data were also protected by federal statute (Public Health Service Act 42 USC) as a consequence of funding from the Agency for Healthcare Research and Quality. The Brigham and Women's Hospital/Partners HealthCare System Human Research Committee approved the procedures for the protocol, and electronic informed consent was obtained from all participants. Work-Hour Validation A random subset of participants (7%) completed daily work/sleep diaries, and these diaries were validated in a separate study using continuous work-hour monitoring by direct observation and polysomnographic recordings [2]. Those completing the work/sleep diaries recorded daily work hours for at least 21 out of 28 d and completed the corresponding monthly survey. Pearson product–moment correlation was used to determine the association between daily average work hours and number of extended-duration work shifts reported in the diary and through the monthly survey. Statistical Analysis Our analysis to determine whether the number of extended-duration shifts worked per month was associated with significant medical errors and with attentional failures during surgery, while examining patients, while on rounds with attending physicians, and during educational events employed a case-crossover component of self-matching [5,6]. Specifically, months were classified according to the number of reported extended-duration shifts worked (i.e., zero, between one and four, and five or more shifts) per month and whether or not a particular outcome occurred at least once during the month. The denominator for our events was thus the intern-month. That is, each participant was considered as a separate stratum in the analysis, and therefore interns acted as their own controls. This case-crossover analysis thus eliminated the need to account for potential between-participant confounders such as age, gender, or medical specialty. A Mantel-Haenszel test was then used to calculate a pooled odds ratio of at least one outcome occurring during months with between one and four, or five or more extended-duration shifts worked (using months with no extended-duration shifts as the comparison group) [7]. To address potential reporting bias, we conducted a sub-analysis of the data from the 682 interns who completed all monthly surveys. In addition, given that the ACGME established new resident work-hour guidelines in 2003, we conducted a sub-analysis in which we included only those intern-months that were in compliance with current ACGME guidelines based on the frequency of extended-duration work shifts (i.e., those intern-months with nine or fewer extended-duration work shifts). To limit this analysis to months in which interns worked full time, months reported to have fewer than 150 h worked were excluded. Odds ratios are reported with 95% confidence intervals [CIs]. SAS 8.2 (SAS Institute [http://www.sas.com]) was used for statistical analysis, and p 24 h) has been reduced (e.g., from a frequency of Q2 to Q3 to Q4 [where Q2 is an extended duration shift occurring every other night, Q3 is an extended duration shift occurring every third night, and Q4 is an extended duration shift occurring every fourth night]). However, the practice of working for more than 24 h consecutively has remained the cornerstone of American postgraduate medical education. In fact, the recent (2003) ACGME work-hour guidelines for postgraduate medical education programs effectively continue to sanction up to nine extended-duration shifts (of up to 30 h consecutively) per month, since every other shift can be an extended-duration work shift under the new ACGME guidelines [29]. Still, interns working extended-duration shifts within these ACGME guidelines reported significant numbers of medical errors, including those that resulted in adverse patient outcomes and fatalities. Furthermore, 83.6% of interns reported working more hours than allowed by ACGME standards in the year following their introduction [30]. These data, collected from interns in all specialties across the United States, are not consistent with the recent suggestions by a member of the ACGME Residency Review Committee in Surgery [31] that safety hazards associated with resident fatigue are limited to a small subset of trainees. Even interns who worked well below the current 80-h ACGME weekly work-hour limits (averaging 64.8 h of work per week), but who continued to work up to one extended-duration shift per week (half the weekly frequency allowed under current ACGME standards), had 8-fold greater odds of reporting an adverse event than those who did not work extended-duration work shifts. This finding is consistent with data from numerous studies documenting that 24 h consecutively of wakefulness impairs short-term memory, degrades neurobehavioral performance, and greatly increases the risk of both errors of commission and omission and attentional failures [23,32,33]. Additionally, Ayas and colleagues recently reported that the odds of an intern having a percutaneous injury increased by 61% after ≥ 20 h at work [34]. These findings are also consistent with the recent demonstration that elimination of extended-duration work shifts reduces attentional failures and serious medical errors among interns working in intensive-care units [2,3]. Our results thus reveal that the practice of scheduling 24-h or greater extended-duration work shifts, as currently sanctioned by the ACGME, may pose a significant increased risk of safety hazards to patients, contribute to the occurrence of medical errors that are attributable to fatigue or sleep deprivation and to consequent preventable fatal and nonfatal adverse events, and may also interfere with the primary educational purpose of residency training. These results have important public policy implications in terms of postgraduate medical education and suggest that directors of training programs should consider alternative coverage schedules for trainees with the objective of eliminating extended-duration shifts. In Europe, where the tradition of extended-duration “on call” shifts originated more than a century ago, work shifts of all physicians (including those in training) have recently been limited to 13 h consecutively [35], thereby eliminating extended-duration work shifts altogether. Fletcher et al. recently published a review of interventions aimed at reducing US resident work hours, including strategies such as day and night float teams and the use of physician extenders [36]. Future studies should explore the applicability of our findings regarding the association between medical errors and extended-duration work shifts to all practicing physicians in the United States. Supporting Information Alternative Language Abstract S1 Translation of the Abstract into Hungarian by S. Kantor (102 KB PDF) Click here for additional data file. Alternative Language Abstract S2 Translation of the Abstract into Polish by L. Kubin (27 KB PDF) Click here for additional data file. Alternative Language Abstract S3 Translation of the Abstract into Portuguese by F. Louzada (22 KB PDF) Click here for additional data file. Alternative Language Abstract S4 Translation of the Abstract into French by C. Gronfier (32 KB PDF) Click here for additional data file. Alternative Language Abstract S5 Translation of the Abstract into Chinese by L. Ling (188 KB PDF) Click here for additional data file. Alternative Language Abstract S6 Translation of the Abstract into Spanish by C. Robles (28 KB PDF) Click here for additional data file. Alternative Language Abstract S7 Translation of the Abstract into Japanese by T. Tanigawa (16.5 KB PDF) Click here for additional data file.
